What is a wind turbine?
A wind turbine is a machine that transforms the kinetic energy of the wind into mechanical or electrical energy. Wind turbines consist of a foundation, a tower, a nacelle and a rotor.
The foundation, prevents the turbine from falling over. The tower holds up the rotor and a nacelle
The nacelle, contains large primary components such as the main shaft, gearbox, generator, transformer and control system.
The rotor, is made of the blades and the hub, which holds them in position as they turn. Most commercial wind turbines have three rotor blades. The length of the blades depends on the size of the turbine and can be more than 80 metres.
What is a wind turbine made of?
The towers are mostly tubular and made of steel or concrete, generally painted light grey. The blades are made of fibreglass, reinforced polyester or wood-epoxy. They are light grey because it is inconspicuous under most lighting conditions. The finish is matt, to reduce reflected light. As turbines are most often seen against the sky, the idea behind painting them white/light grey is to make them as visually unobtrusive as possible.
It was also decided that turbines were to be of bright colour to enable them to be early detected by pilots. However, several makes of turbine have now started to paint the bottom half of the tower section green in further attempts to make them blend in with the countryside.
Why do some wind turbines have two and others have three blades?
The majority of modern commercial wind turbines have three blades, as they produce the optimum amount of power.
Two bladed machines are cheaper and lighter, with higher running speeds which reduces the cost of the gearbox, and they are easier to install.
They perform almost as well as three blade turbines. However they can be noisier and are not as visually attractive.
Why do some of the wind turbines on a Windfarm sometimes stand still?
Turbines sometimes have to be stopped for maintenance, for repairing components or if there is a failure that needs to be checked.
Another reason can be too little or too much wind: if the wind is too strong, the turbine needs to be shut down because it could be damaged.
Are wind turbines noisy?
The noise of wind turbines has been reduced significantly. Improved design has drastically reduced the noise of mechanical components so that the most audible sound is that of the wind interacting with the rotor blades.
This is similar to a light swishing sound, and much quieter than other types of modern-day equipment. Even in generally quiet rural areas, the sound of the blowing wind is often louder than the turbines.
How long does a wind turbine work for?
A wind turbine can continue producing energy for up to 20-25 years and can run for as long as 120, 000 hours throughout their life time.
During this time some parts may require replacing and at the end of their lives they can be decommissioned and replaced with new models within a few days.
Why do turbine blades need washed and how often.
Insects and dirt may affect the aerodynamic properties of the blades, which leads to decreased productivity of the wind turbine. moss and algae growth on the blades leading edge can reduce the wind turbine power output by as much as 25 per cent.
It is recommended that wind turbine blades are cleaned and inspected for damage every two years if dirt build-up is substantial.